Prevention of Thromboembolism in Spinal Cord Injury

Introduction:

Thromboembolism is a term that refers to the dislodgement of a clot that is formed initially in the blood vessels. This is dangerous because the clot can travel through the blood, affecting all the organs and ultimately resulting in organ failure or damage. Thromboembolism can either be present with deep vein thrombosis, pulmonary embolism, or both. Deep vein thrombosis is a condition in which a clot is formed in one of the deep veins of the legs. Pulmonary embolism is a condition in which a blood clot is formed in the arteries of the lungs. There are two types of thromboembolism:

1. Venous Thromboembolism: It is formed in veins (blood vessels that carry blood from organs to the heart), and it often occurs in the legs with a condition called deep vein thrombosis (DVT). A pulmonary embolism occurs when a clot travels to the lung and obstructs blood flow. Following an acute spinal injury, the most common complication is venous thromboembolism.

2. Arterial Thromboembolism: It is formed in arteries (blood vessels that carry blood from the heart to organs) and often causes ischemia (restriction of blood supply). If this occurs in the heart, it will result in a heart attack. It happens when the thrombus, formed somewhere in the circulation, travels to a peripheral artery and embolizes (blocks blood supply).

What Are the Various Causes of Spinal Cord Injury?

Spinal cord injury occurs due to trauma or damage to the spinal cord. Spinal cord injury can have many complications, including disability. Hence swift intervention is necessary to avoid such ailments. Spinal cord injury can occur due to the following reasons:

1. Road traffic accidents and accidental falls.

2. Obesity.

3. Vertebral fractures in patients with osteoporosis.

4. An assault that may result in penetrating injuries.

5. Blood disorders.

6. Tumors.

7. Accidental injury during spinal injections.

8. Infectious conditions.

9. Spondylosis is a type of arthritis of the spine causing neck pain which may be a result of aging and wear and tear of the muscles.

10. Developmental conditions.

How Does Thromboembolism Occur?

Patients develop thromboembolism due to three primary reasons, which is termed Virchow's triad:

1. Venous Stasis: The pooling of blood in the veins of the leg that had long been immobilized due to trauma or paralysis can cause thromboembolism.

2. Endothelial Integrity: If the integrity of endothelium (inner lining of the vessel wall) is compromised, then there is an alteration in the anticoagulant factors, and this will lead to thromboembolism and other complications.

3. Hypercoagulability: If the coagulability of the blood is more than the normal range, then there will be increased platelet aggregation and an increase in the clotting factors of blood. This will lead to the formation of thromboembolism.

What Are the Risk Factors?

• Prolonged bed rest and immobilization.

• Old age.

• A previous episode of venous thromboembolism.

• Surgery is done in the lower proximity, such as the legs, knees, and pelvis.

• Reduced cardiac output, such as in congestive heart failure.

• Women who are pregnant and those using oral contraceptives.

• Trauma or injury.

What Are the Symptoms?

The classic symptom is edema or swelling in one or two legs. Mild pain may be present in some patients. Pressure or compression is felt in the calf muscles and thigh muscles. Unexplained fever is also present.

How Is It Diagnosed?

A thorough clinical evaluation is done to assess for symptoms relating to thromboembolism. The following tests are done to evaluate thromboembolism:

1. D-Dimer Assay - It is a non-invasive test for predicting the presence of deep vein thrombosis.

2. Radiocontrast Venography - It is a technique in which a contrast dye is injected through veins to detect the normal flow of blood.

3. Doppler Ultrasonography - It is a technique in which blood flow to the veins is detected by sound waves.

4. Ventilation / Perfusion Lung Scanning - Ventilation and perfusion lung scan are done to assess the airflow and blood supply in the lung, respectively.

What Are the Treatment Methods?

Thromboembolectomy is a surgical procedure done to restore the patency of the affected vessel wall. An incision is placed over the vein, and a catheter or thin tube is inserted. The clot is removed, and the blood flow is restored. It is a less invasive procedure and takes up to two to three hours, and is done under local anesthesia or sedation.

What Are the Preventive Measures?

Thromboembolism after a spinal cord injury can be prevented by the following measures:

1. Prophylaxis: Prophylactic therapy should be started as early as possible. Avoid the use of Warfarin, which is an antagonist of vitamin K (helpful in clotting) due to bleeding risk, and the dose adjusting is also difficult. Low molecular weight Heparin (LMWH) can be used once active bleeding is ruled out. Use oral anticoagulants such as Rivaroxaban, Dabigatran, and Apixaban during recovery. Acute deep vein thrombosis can be treated with Enoxaparin. This anticoagulant thromboprophylaxis should be carried out at least up to eight weeks after spinal cord injury.

2. Mobilization: Mobilization of the patient can be done once the patient is stable. Passive stretching can be done to prevent stasis. Active and passive range of motion exercises reduces the incidence of venous stasis. Elevation of the legs can also improve blood flow and prevent venous stasis.

3. Pneumatic Compression Devices: They are a type of inflatable sleeve that can be worn on the leg, which will increase the blood flow to the legs. They lessen the risk of bleeding even in high-risk patients. So, patients are advised to wear it all the time except during bathing.

4. Graduated Compression Stockings: They are a type of stockings that have different levels of compression and are strongest near the ankle and reduce as it goes up. It will help control edema (swelling). These devices are removed during an examination to see if an injury is caused.

5. Electrical Stimulation: This is a technique in which an electric current is passed on to the affected leg to promote venous blood flow and increase the speed of flow. Combining the prophylactic measures with this stimulation can greatly reduce the risk of thromboembolism formation.

6. Inferior Vena Cava (IVC) Filters: This is a medical device that is placed in the inferior vena cava to prevent the clot from traveling to the lungs. This can be used in patients who are contraindicated for therapeutic anticoagulation. The inferior vena cava is the largest vein in the body and carries blood to the heart from the legs, feet, pelvis, and abdomen.

7. Arteriovenous (AV) Impulse System: This is a foot compression device that mimics the normal activities done by the legs for weight bearing, such as walking. In this way, the impulse system helps in improved circulation in the legs preventing deep vein thrombosis.

Conclusion:

Thromboembolism after spinal cord injury is the biggest cause of morbidity. The persistence of this condition can lead to prolonged edema and pressure ulcers in the legs. But if anticoagulant thromboprophylaxis is done in the initial stages of admission after an injury, thromboembolism can be prevented. If the complications are reduced or nullified, then the treatment goal can be focused on the actual injury, that is, to the spine. Early diagnosis and preventive measures have to be taken to prevent the formation of thromboembolism.